Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

Included is an emulsion aggregation toner formulation having at least one
latex and a combination of at least two waxes, wherein one wax is a
synthetic wax, and another wax is a natural wax, and further including a
developer containing a carrier and the just-described toner.

Claims:

1. An emulsion aggregation toner formulation comprising at least one
latex and a combination of a least two waxes.

2. An emulsion aggregation toner formulation as claimed in claim 1,
comprising any combination of a synthetic and/or a natural wax.

3. An emulsion aggregation toner formulation as claimed in claim 2,
wherein said wax is a polyalkene wax.

4. An emulsion aggregation toner formulation as claimed in claim 3,
wherein said polyolefin wax is selected from the group consisting of
polyethylenes and polypropylenes.

5. An emulsion aggregation toner formulation as claimed in claim 4,
wherein said polyolefin wax is a polyethylene.

6. An emulsion aggregation toner formulation as claimed in claim 1,
wherein said wax is a natural vegetal wax.

7. An emulsion aggregation toner formulation as claimed in claim 6,
wherein said natural vegetal wax is selected from the group consisting of
Carnauba wax, candelilla wax, Japan wax, and bayberry wax.

9. An emulsion aggregation toner formulation as claimed in claim 1,
wherein said waxes are present in the emulsion aggregation toner
formulation in a weight ratio of from about 40/60 to about 60/40.

10. An emulsion aggregation toner formulation as claimed in claim 9,
wherein said weight ratio is from about 58/42 to about 42/58.

11. An emulsion aggregation toner formulation as claimed in claim 10,
wherein said weight ratio is from about 55/45 to about 45/55.

12. An emulsion aggregation-toner formulation as claimed in claim 1,
wherein said wax is a polyolefin having a Mw of from about 400 to about
850.

13. An emulsion aggregation toner formulation as claimed in claim 12,
wherein said Mw is from about 650 to about 800.

14. An emulsion aggregation toner formulation as claimed in claim 13,
wherein said Mw is from about 700 to about 750.

15. An emulsion aggregation toner formulation as claimed in claim 1,
wherein at least one latex comprises a core latex and a shell latex.

16. An emulsion aggregation toner formulation as claimed in claim 1,
wherein said at least one latex comprises a core latex, a shell latex,
and a gel latex.

17. A developer composition comprising a carrier and the emulsion
aggregation toner formulation of claim 1.

18. An emulsion aggregation toner formulation comprising at least one
latex, a colorant, and a combination of waxes, wherein a wax is a
polyolefin wax, and a wax is a natural vegetal wax, and wherein said
waxes are present in said emulsion aggregation toner formulation in a
weight ratio of from about 40/60 to about 60/40.

19. An emulsion aggregation toner formulation comprising a core latex, a
shell latex, a gel latex, a colorant, and a combination of a at least two
waxes, wherein one wax is a polyethylene wax having a Mw of from about
700 to about 750, and one wax is a Carnauba wax, and wherein said wax
combination is present in said emulsion aggregation toner formulation in
a weight ratio of from about 40/60 to about 60/40.

Description:

BACKGROUND

[0001] The present disclosure relates generally to toner and developer
compositions, useful in electrostatographic, electrophotographic,
xerographic, and the like machines, including printers, copiers,
scanners, facsimiles, and the like, and including digital and
image-on-image machines. More specifically, the disclosure relates to
toner compositions comprising-dual wax combination. In embodiments, the
dual wax combination comprises a polyethylene wax in combination with a
Carnauba wax.

[0002] Methods of preparing emulsion aggregation (EA) type toner are
known. Toners may be formed by aggregating a colorant with a latex
polymer formed by batch or semi-continuous emulsion polymerization. For
example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby
incorporated by reference in its entirety, discloses a semi-continuous
emulsion polymerization process for preparing a latex by first forming a
seed polymer. In particular, the '943 patent describes a process
comprising: (a) conducting a pre-reaction monomer emulsification
comprising emulsification of the polymerization reagents of monomers,
chain transfer agent, a disulfonate surfactant or surfactants, and
optionally, an initiator, wherein the emulsification is accomplished at a
low temperature of, for example, from about 5° C. to about
40° C.; (b) preparing a seed particle latex by aqueous emulsion
polymerization of a mixture comprising (i) part of the monomer emulsion,
for example, from about 0.5 to about 50 percent by weight, or from about
3 to about 25 percent- by weight, of the monomer emulsion prepared in
(a), and (ii) a free radical initiator, from about 0.5 to about 100
percent by weight, or from about 3 to about 100 percent by weight, of the
total initiator used to prepare the latex polymer at a temperature of
from about 35° C. to about 125° C., wherein the reaction of
the free radical initiator and monomer produces the seed latex comprising
latex resin wherein the particles are stabilized by surfactants; (c)
heating and feed adding to the formed seed particles the remaining
monomer emulsion, from about 50 to about 99.5 percent by weight, or from
about 75 to about 97 percent by weight, of the monomer emulsion prepared
in (b), and optionally a free radical initiator, from about 0 to about
99.5 percent by weight, or from about 0 to about 97 percent by weight, of
the total initiator used to prepare the latex polymer at a temperature
from about 35° C. to about 125° C.; and (d) retaining the
above contents in the reactor at a temperature of from about 35°
C. to about 125° C. for an effective time period to form the latex
polymer, for example from about 0.5 to about 8 hours, or from about 1.5
to about 6 hours, followed by cooling. Other examples of
emulsion/aggregation/coalescing processes for the preparation of toners
are illustrated in U.S. Pat. Nos. 5,290,654, 5,278,020, 5,308,734,
5,370,963, 5,344,738, 5,403,693, 5,418,108, 5,364,729, and 5,346,797, the
disclosures of each of which are hereby incorporated by reference in
their entirety. Other processes are disclosed in U.S. Pat. Nos.
5,348,832, 5,405,728, 5,366,841, 5,496,676, 5,527,658, 5,585,215,
5,650,255, 5,650,256 and 5,501,935, the disclosures of each of which are
hereby incorporated by reference in their entirety.

[0003] Currently, some known EA toner formulations use a single wax (for
example, polyolefin, such as polyethylene or polypropylene). The present
disclosure describes the replacement of the use of a single polyolefin
with a combination of synthetic and a second, different wax. The use of
the combination of different waxes is believed to increase the release
function of the EA toner. The result is ease of cleaning of the
photoreceptor. In addition, polyolefin waxes are expensive. Therefore, by
cutting back on the amount of wax by using a combination of two different
waxes, an EA toner can be produced at a lower cost.

[0004] Toner builds up on the thermister, striper fingers and the cleaning
web. This toner deposits itself on the back of copies. The dual wax
formulation allows greater release properties and a more uniform
distribution of surface additives and consequently a more uniform charge
distribution on the surface of the toner. This eliminates or minimizes
toner deposits on the stripper fingers, thermister, and cleaning web.

[0005] Therefore, it is desirable to provide a toner which solves or
reduces fusing defects. It is further desired to provide an EA toner that
can be prepared with less wax, in order to decrease the cost of
production of the EA toner. The lower amount of total wax yields less wax
on the toner surface. This allows lower amounts of external toner
additives to be used and lowers the cost. Less wax on the surface also
facilitates increased toner flow and a more uniformed surface charge. The
lower melting wax would allow faster copier speeds and/or lower fusing
temperatures.

SUMMARY

[0006] Embodiments include an emulsion aggregation toner formulation
comprising a binder resin and a combination of a first and second wax,
wherein the first wax is a synthetic wax, and the second wax is a natural
wax.

[0007] Embodiments also include an emulsion aggregation toner formulation
comprising a binder resin, colorant, and a combination of a first and
second wax, wherein the first wax is synthetic wax, and the second wax is
a natural wax, and wherein the first and second wax are present in said
emulsion aggregation toner formulation in a weight ratio of from about
40/60 to about 60/40.

[0008] Further, embodiments include an emulsion aggregation toner
formulation comprising a binder resin, colorant, and a combination of a
first and second wax, wherein the first wax is a polyethylene wax having
a Mw of from about 700 to about 750, and having a degree of crystallinity
as calculated by heat of melting and as measured by DSC of from about 55
to about 100 percent, and the second wax is a Carnauba wax, and wherein
said first and second wax are present in the emulsion aggregation toner
formulation in a weight ratio of from about 40/60 to about 60/40.

[0009] In addition, embodiments include a developer including a carrier
and an emulsion aggregation toner formulation comprising a binder resin
and a combination of a first and second wax, wherein the first wax is a
synthetic wax, and the second wax is a natural wax.

DETAILED DESCRIPTION

[0010] In embodiments, the toner is an emulsion aggregation type toner
prepared by the aggregation and fusion of latex resin particles with a
colorant.

[0011] In embodiments, the latex which may be used in forming toner
includes, for example, submicron non-crosslinked resin particles in the
size range of, for example, from about 50 to about 500 nanometers, or
from about 100 to about 400 nanometers in volume average diameter as
determined, for example, by a Brookhaven nanosize particle analyzer. The
non-crosslinked resin is generally present in the toner composition of
from about 75 to about 98, or from about 80 to about 95 weight percent of
the toner or the solids of the toner. The expression "solids" can refer
to the latex, colorant, wax, and any other optional additives in the
toner composition. One or more additives may be included such as
surfactants, coagulants, waxes, surface additives, and optionally
mixtures thereof. In embodiments, one or more is from about 1 to about 20
or from about 3 to about 10.

[0012] In embodiments, the non-crosslinked resin in the latex is derived
from the emulsion polymerization of monomers including, but not limited
to, styrenes, butadienes, isoprenes, acrylates, methacrylates,
acrylonitriles, acrylic acid, methacrylic acid, itaconic or beta carboxy
ethyl acrylate (β-CEA), polyesters, and the like, and mixtures
thereof.

[0014] In embodiments, the latex may be prepared by a batch or a
semicontinuous polymerization resulting in submicron non-crosslinked
resin particles suspended in an aqueous phase containing a surfactant.
Examples of suitable surfactants include ionic or nonionic surfactants in
an amount of from about 0.01 to about 15, or from about 0.01 to about 5
weight percent of total solids.

[0018] In embodiments, the non-crosslinked resin may be prepared with
initiators, such as water-soluble initiators and organic soluble
initiators. Exemplary water-soluble initiators are ammonium and potassium
persulfates. These can be added in suitable amounts, such as from about
0.1 to about 8, or from about 0.2 to about 5 weight percent of the
monomer. Examples of organic soluble initiators include Vazo peroxides,
such as Vazo 64, 2-methyl 2-2'-azobis propanenitrile, and Vazo 88,
2-2'-azobis isobutyramide dehydrate in a suitable amount, such as from
about 0.1 to about 8, or from about 0.2 to about 5 weight percent of the
monomer.

[0019] Known chain transfer agents can also be used to control the
molecular weight properties of the resin if prepared by emulsion
polymerization. Examples of chain transfer agents include dodecane thiol,
dodecylmercaptan, octane thiol, carbon tetrabromide, carbon tetrachloride
and the like, in various suitable amounts, such as from about 0.1 to
about 20, or from about 0.2 to about 10 percent by weight of monomer.

[0020] Resin particles may also be produced by a polymer microsuspension
process as disclosed in U.S. Pat. No. 3,674,736, polymer solution
microsuspension process as disclosed in U.S. Pat. No. 5,290,654, the
disclosure of both of these references is hereby incorporated by
reference in their entirety, mechanical grinding processes, or other
known processes.

[0021] In embodiments, gel latex may be added to the non-crosslinked latex
resin suspended in the surfactant. Gel latex may refer in embodiments, to
a crosslinked resin or polymer, or mixtures thereof, or a non-crosslinked
resin as described above, that has been subjected to crosslinking.

[0022] The gel latex may include, submicron crosslinked resin particles
having a size of from about 10 to about 200, or from about 20 to 100
nanometers in volume average diameter. The gel latex may be suspended in
an aqueous phase of water containing a surfactant, wherein the surfactant
can be in an amount from about 0.5 to about 5, or from about 0.7 to about
2 percent by weight of total solids.

[0024] A crosslinker, such as divinyl benzene or other divinyl aromatic or
divinyl acrylate or methacrylate monomers may be used in the crosslinked
resin. The crosslinker may be present in an amount of from about 0.01 to
about 25, or from about 0.5 to about 15 percent by weight of the
crosslinked resin.

[0025] The crosslinked resin particles may be present in an amount of from
about 0.1 to about 50, or from about 1 to about 20 percent by weight of
the toner.

[0026] In embodiments, the gel latex may be a mixture of a crosslinked
resin and a non-crosslinked resin.

[0027] Optionally, a second latex can be added to the aggregated
particles. The second latex may include, for example, submicron
non-crosslinked resin particles. The second latex may be added in an
amount of from about 10 to about 40 percent by weight of the initial
latex, and in embodiments in an amount of from about 15 to about 30
percent by weight of the initial latex, to form a shell or coating on the
toner aggregates wherein the thickness of the shell is from about 200 to
about 800 nanometers, and in embodiments from about 250 to about 750
nanometers.

[0028] In embodiments of the present disclosure, the latex and the second
latex may be the same non-crosslinked resin.

[0029] In embodiments, the core latex and the second shell latex may be
different non-crosslinked resins.

[0030] The core, shell latexes and optional gel latex may be added to a
colorant and/or a wax to form a toner. In embodiments, the colorant may
be in a dispersion and the wax may also be in a dispersion. The colorant
dispersion includes, for example, submicron colorant particles having a
size of, from about 50 to about 500, or from about 100 to about 400
nanometers in volume average diameter. The colorant particles may be
suspended in an aqueous water phase containing an anionic surfactant, a
nonionic surfactant, or mixtures thereof. In embodiments, the surfactant
may be ionic and is from about 1 to about 25, or from about 4 to about 15
percent by weight of the colorant.

[0035] The toner may also include any known charge additives in amounts of
from about 0.1 to about 10, or from about 0.5 to about 7 weight percent
of the toner.

[0036] Where used, wax dispersions include submicron wax particles having
a size of from about 50 to about 500 or from about 100 to about 400
nanometers in volume average diameter, suspended in an aqueous phase of
water and an ionic surfactant, nonionic surfactant, or mixtures thereof.
The ionic surfactant or nonionic surfactant may be present in an amount
of from about 0.01 to about 10, or from about 0.2 to about 5 percent by
weight of the wax.

[0037] In embodiments, a combination of two different waxes is used in the
EA toner formulation herein. Examples of suitable release agents or waxes
include natural vegetal wax, natural animal wax, mineral wax and/or
synthetic wax. The term "natural vegetal wax" means a wax that occurs in
its natural form and having originates from a variety of different
plants, and is not synthetic. Examples of natural vegetal waxes include,
for example, Carnauba wax, candelilla wax, Japan wax, and bayberry wax.
Examples of natural animal waxes include, for example, beeswax, punic
wax, lanolin, lac wax, shellac wax, and spermaceti wax. Mineral waxes
include, for example, paraffin wax, microcrystalline wax, montan wax,
ozokerite wax, ceresin wax, petrolatum wax, and petroleum wax. Synthetic
waxes of the present disclosure include, for example, Fischer-Tropsch
wax, acrylate wax, fatty acid amide wax, silicone wax,
polytetrafluoroethylene wax, polyethylene wax, polypropylene wax, and
mixtures thereof. Other examples of waxes include polyolefins such as
polypropylenes, polyethylenes, and the like, such as those commercially
available from Allied Chemical and Baker Petrolite COrporation, wax
emulsions available from Michaelman Inc. and the Daniels Products
Company, Epolene N-15® commercially available from Eastman Chemical
Products, Inc., Viscol 550-P®, a low weight average molecular weight
polypropylene available from Sanyo Kasei K.K., and similar materials.
Examples of functionalized waxes include amines, amides, for example Aqua
Superslip 6550®, Superslip 6530® available from Micro Powder Inc.;
fluorinated waxes, for example Polyfluo 190®, Polyfluo 200®,
Polyfluo 523XF®, Aqua Polyfluo 411®, Aqua Polysilk 19®, Polysilk
14® available from Micro Powder Inc.; mixed fluorinated, amide waxes,
for example Microspersion 19® also available from Micro Powder Inc.;
imides, esters, quatemary amines, carboxylic acids or acrylic polymer
emulsion, for example Joncryl 74®, 89®, 130®, 537®, and
538®, all available from SC Johnson Wax; chlorinated polypropylenes
and polyethylenes available from Allied Chemical and Petrolite
Corporation, and from SC Johnson Wax. Example of an ester wax would be
Licowax F® available from Clariant Corporation. Such waxes can
optionally be fractionated or distilled to provide specific cuts that
meet viscosity and/or temperature criteria wherein the upper limit of
viscosity is 10,000 cps and the temperature upper limit is 120° C.

[0038] In embodiments, the wax comprises a wax in the form of a dispersion
comprising, for example, a wax having a particle diameter of about 100
nanometers to about 500 nanometers or about 100 nanometers to about 300
nanometers, water, and an anionic surfactant or a polymeric stabilize,
and optionally a nonionic surfactant. In embodiments, the wax comprises
polyethylene wax particles, such as POLYWAX® 655, POLYWAX® 850,
POLYWAX® 725, POLYWAX® 500, POLYWAX® 400 (the POLYWAX®
waxes being commercially available from Baker Petrolite) and, for
example, fractionated/distilled waxes which are cuts of commercial
POLYWAX® 655 designated here as X1214, X1240, X1242, X1244, and the
like, but are not limited to POLYWAX® 655 cuts. The surfactant used
to disperse the wax can be an anionic surfactant, although not limited
thereto, such as, for example, Neogen RK® commercially available from
Daiichi Kogyo Seiyaku or TAYCAPOWER® BN2060 commercially available
from Tayca Corporation or Dowfax available from DuPont.

[0039] In embodiments, at least one of the waxes has a degree of
crystallinity (Xc) as calculated by heat of melting or heat of fusion or
enthalpy, and as measured by DSC, of from about 55 to about 100 percent,
or from about 60 to about 98 percent, or from about 70 to about 95
percent, or from about 75 to about 90 percent.

[0040] The melt viscosity of the wax for example at 92° C., is less
than or about 10,000 centipoise, or from about 5 to about 10,000
centipoise, and the viscosity at 110° C. is less than or equal to
100 centipoise, or from about 1 to about 100 centipoise, irrespective of
the heating or the melting cycle. Furthermore the useful temperature for
coalescence/fusion step can be lower than 92° C., for example as
low as 88° C.

[0041] In embodiments, the natural wax has an onset temperature of from
about 40 to about 70° C., and an offset temperature of from about
70 to about 90° C., during the heat up cycle (i.e., melting), as
measured by a DSC when the heating rate is 10° C./min.

[0042] In embodiments, the synthetic wax has an onset melt temperature of
from about 65 to about 75° C., and an offset temperature of from
about 95 to about 100° C.

[0043] In embodiments, the synthetic wax has a Mn, and each and all may
fall within the ranges of from about 400 to about 850 or from about 650
to about 800 or from about 700 to about 750, or about 725.

[0044] The total wax combination in a toner material is, for example, in
an amount of about 1 to about 20 percent, or from about 2 to about 15
percent by weight based upon the total weight of the composition.

[0045] In embodiments, a combination of different waxes can be used. In
embodiments, a synthetic and a natural wax are used together. In
embodiments, a combination of a polyolefin wax and Carnauba wax are used.
In specific embodiments, the wax combination comprises a polyethylene wax
and Carnauba wax.

[0046] In embodiments, the first and second waxes are present in weight
ratios of from about 40/60 to about 60/40, or from about 58/42 to about
42/58, or from about 55/45 to about 45/55, or about 50/50. In
embodiments, a polyethylene (such as Polywax 655, 725, or the like) and a
natural vegetal wax, such as Carnauba wax, are used in approximately a
50/50 weight ratio, although any of the above ratios can be used.

[0047] The resultant blend of latex dispersion, optional gel latex
dispersion, colorant dispersion, and wax dispersion may be stirred and
heated to a temperature of from about 45° C. to about 65°
C., in embodiments of from about 48° C. to about 63° C.,
resulting in toner aggregates of from about 4 to about 8, or from about 5
microns to about 7 microns in volume average diameter.

[0048] In embodiments, a coagulant may be added during or prior to
aggregating the latex, the aqueous colorant dispersion, the wax
dispersion and the optional gel latex. The coagulant may be added over a
period of time from about 1 to about 5 or from about 1.25 to about 3
minutes. The time above is lab scale; this would be different in
manufacturing.

[0049] Examples of coagulants include polyaluminum halides such as
polyaluminum chloride (PAC), or the corresponding bromide, fluoride, or
iodide, polyaluminum silicates such as polyaluminum sulfo silicate
(PASS), and water soluble metal salts including aluminum chloride,
aluminum nitrite, aluminum sulfate, potassium aluminum sulfate, calcium
acetate, calcium chloride, calcium nitrite, calcium oxylate, calcium
sulfate, magnesium acetate, magnesium nitrate, magnesium sulfate, zinc
acetate, zinc nitrate, zinc sulfate and the like. One suitable coagulant
is PAC, which is commercially available and can be prepared by the
controlled hydrolysis of aluminum chloride with sodium hydroxide.
Generally, PAC can be prepared by the addition of two moles of a base to
one mole of aluminum chloride. The species is soluble and stable when
dissolved and stored under acidic conditions if the pH is less than about
5. The species in solution is believed to be of the formula
Al13O4(OH)24(H2O)12 with about 7 positive
electrical charges per unit.

[0050] In embodiments, suitable coagulants include a polymetal salt such
as, for example, polyaluminum chloride (PAC), polyaluminum bromide, or
polyaluminum sulfosilicate. The polymetal salt can be in a solution of
nitric acid, or other diluted acid solutions such as sulfuric acid,
hydrochloric acid, citric acid or acetic acid. The coagulant may be added
in amounts from about 0.02 to about 0.3 percent by weight of the toner,
and in embodiments from about 0.05 to about 0.2 percent by weight of the
toner.

[0051] Once the desired final size of the particles is achieved with a
volume average diameter of from about 4 to about 9 microns, or from about
5.6 to about 8 microns, the pH of the mixture may be adjusted with a base
to a value of from about 4 to about 7, or from about 6 to about 6.8. The
base may include any suitable base . such as, alkali metal hydroxides
including sodium hydroxide, potassium hydroxide, and ammonium hydroxide.
The alkali metal hydroxide may be added in amounts from about 6 to about
25 or from about 10 to about 20 percent by weight of the mixture.

[0052] The pH of the mixture is then lowered to from about 6.5 to about
3.0, or from about 6.0 to about 3.5 with, for example, an acid to
protonate and better coalesce the toner aggregates. Suitable acids
include nitric acid, sulfuric acid, hydrochloric acid, citric acid, or
acetic acid. The amount of acid added may be from about 4 to about 30 or
from about 5 to about 15 percent by weight of the mixture. The mixture
temperature may be from 70° C. to about 93° C. , or from
75° C. to about 87° C.

[0053] The mixture is subsequently coalesced. Coalescing may include
stirring and heating at a temperature of from about 90° C. to
about 99° C., for a period of from about 0.5 to about 6, or from
about 2 to about 5 hours.

[0054] The pH of the mixture may be adjusted with a base to a value of
from about 3.5 to about 7, or from about 3.7 to about 6.0. The base may
include any suitable base such as, alkali metal hydroxides including
sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

[0055] The mixture is then cooled. Cooling may be at a temperature of from
about 20° C. to about 40° C., or from about 22° C.
to about 30° C. over a period time from about 1 to about 8, or
from about 1.5 to about 5 hours.

[0056] The toner in the mixture is then recovered via wet sieving or
filtering the mixture and the coalesced particles thereby obtained are
washed and dried. The washing includes filtering and reslurrying a filter
cake. The pH of the mixture is adjusted to from about 3 to about 7, or
from about 4 to about 6. Typically, the pH is adjusted with a base such
as sodium hydroxide, ammonia hydroxide, or the like. In embodiments, the
base is added to a heated emulsion aggregation toner. The emulsion
aggregation toner may be heated to a temperature of from about 40°
C. to about 80° C., or from about 50° C. to about
70° C. Once the desired pH has been obtained, the slurry is sieved
and the mother liquor decanted. In embodiments, the wet cake toner is
then reslurried in clean, deionized or distilled water, typically having
a pH of from about 6 to about 10, or from about 7 to about 9. The mixture
is then filtered, and the resulting filter cake is washed one or more
times with deionized or distilled water. The pH may be reduced with an
acid such as HCl, HNO3 or other similar types during the washing
with deionized water or distilled water. The acid may reduce the pH to
from about 8 to about 3, or from about 6 to about 3.5. The washing with
deionized distilled water may be at a temperature of from about
30° C. to about 70° C., and in embodiments from about
35° C. to about 55° C.

[0057] In embodiments, the pH of coalesced toner slurry is adjusted with a
base to about 10, followed by one or more deionized water or distilled
water washes. During the deionized or distilled water wash, the pH of the
slurry is adjusted with an acid to about 4. In embodiments, three washes
with deionized or distilled water may be used. In embodiments, the pH of
the slurry is adjusted with an acid during the second wash.

[0058] Drying of the toner is typically carried out at a temperature of
from about 35° C. to about 75° C., or from about 45°
C. to about 60° C. for a period of time from about 1 to about 10
hours, or from about 2 to about 4 hours. The drying may be continued
until the moisture level of the particles is below a set target of less
than about 1% by weight or less than about 0.5% by weight.

[0059] Surface additives can be added to the toner compositions of the
present disclosure after washing or drying. Examples of such surface
additives include, for example, metal salts, metal salts of fatty acids,
colloidal silicas, metal oxides, strontium titanates, mixtures thereof,
and the like. Surface additives may be present in an amount of from about
0.1 to about 10, or from about 0.5 to about 7 weight percent of the
toner. Example of such additives include those disclosed in U.S. Pat.
Nos. 3,590,000, 3,720,617, 3,655,374 and 3,983,045, the disclosures of
each of which are hereby incorporated by reference in their entirety.
Other additives include zinc stearate and AEROSIL R972® available
from Degussa. The coated silicas of U.S. Pat. Nos. 6,190,815 and
6,004,714, the disclosures of each of which are hereby incorporated by
reference in their entirety, can also be present in an amount of from
about 0.05 to about 5, or from about 0.1 to about 2 percent of the toner,
which additives can be added during the aggregation or blended into the
formed toner product.

[0060] The imaging process includes the generation of an image in an
electronic printing apparatus and thereafter developing the image with a
toner composition of the present disclosure. The formation and
development of images on the surface of photoconductive materials by
electrostatic means is well known. The basic xerographic process involves
placing a uniform electrostatic charge on a photoconductive insulating
layer, exposing the layer to a light and shadow image to dissipate the
charge on the areas of the layer exposed to the light and developing the
resulting latent electrostatic image by depositing on the image a
finely-divided electroscopic material referred to in the art as "toner".
The toner will normally be attracted to the discharged areas of the
layer, thereby forming a toner image corresponding to the latent
electrostatic image. This powder image may then be transferred to a
support surface such as paper. The transferred image may subsequently be
permanently affixed to the support surface as by heat.

[0061] Developer compositions can be prepared by mixing the toners
obtained with the embodiments of the present disclosure with known
carrier particles, including coated carriers, such as steel, ferrites,
and the like. See, for example, U.S. Pat. Nos. 4,937,166 and 4,935,326,
the disclosures of each of which are hereby incorporated by reference in
their entirety. The toner-to-carrier mass ratio of such developers may be
from about 2 to about 20, or from about 2.5 to about 5 percent of the
developer composition. The carrier particles can include a core with a
polymer coating thereover, such as polymethylmethacrylate (PMMA), having
dispersed therein a conductive component like conductive carbon black.
Carrier coatings include silicone resins, fluoropolymers, mixtures of
resins not in close proximity in the triboelectric series, thermosetting
resins, and other known components.

[0062] The toner described herein can also be used in single component
development, and in non-magnetic development.

[0063] Development may occur via discharge area development. In discharge
area development, the photoreceptor is charged and then the areas to be
developed are discharged. The development fields and toner charges are
such that toner is repelled by the charged areas on the photoreceptor and
attracted to the discharged areas. This development process is used in
laser scanners. Development can also be charged-area development.

[0064] Development may be accomplished by the magnetic brush development
process disclosed in U.S. Pat. No. 2,874,063, the disclosure of which is
hereby incorporated by reference in its entirety. This method entails the
carrying of a developer material containing toner of the present
disclosure and magnetic carrier particles by a magnet. The magnetic field
of the magnet causes alignment of the magnetic carriers in a brush like
configuration, and this "magnetic brush" is brought into contact with the
electrostatic image bearing surface of the photoreceptor. The toner
particles are drawn from the brush to the electrostatic image by
electrostatic attraction to the discharged areas of the photoreceptor,
and development of the image results. In embodiments, the conductive
magnetic brush process is used wherein the developer comprises conductive
carrier particles and is capable of conducting an electric current
between the biased magnet through the carrier particles to the
photoreceptor.

[0065] The following Examples are being submitted to illustrate
embodiments of the present disclosure. These Examples are intended to be
illustrative only and are not intended to limit the scope of the present
disclosure. Also, parts and percentages are by weight unless otherwise
indicated.

EXAMPLES

Example 1

[0066] Emulsion aggregation toner was prepared as follows. A toner slurry
was prepared by combining a latex dispersion, a 50/50 mixture of
Polywax® 725 and Carnauba wax, a latex, and a colorant dispersion
Regal 330 carbon black. Specifically, 596.6 grams of distilled water,
265.8 grams core latex (41.4% solids, Tg=59.4° C., Mw=36.6 k,
size=223 nm), 97.9 grams gel latex (10% solids), and 126.1 grams pigment
(17.0% solids). The mixture was placed in a 2-liter reactor set at
20° C. The materials were homogenized for 30 seconds at 4,000 rpm.
While homogenizing, 93.74 grams of the wax combination (30% solids) was
added over 30 seconds. After 1 minute, about 42.5 grams of a 10% solution
of polyaluminum chloride was added over 3 minutes. Homogenization
continued for 20 minutes. The homogenizer was replaced with a single A200
impeller, and the mixing continued at 300 RPM. The reactor was set to
59° C., and the particle size was monitored. When the particle
size reached 4.5 microns, 173.1 grams of shell latex (41.4% solids,
Tg=59.4° C., Mw=36.6 k, size=223 nm) was added over 11 minutes.
When the particle size reached 5.9 microns, the mixture was subjected to
freeze reaction with a 4% NaOH solution. The particles were then
coalesced at 96° C., washed, and then dried.

[0070] The combination of two different types of wax was incorporated into
parent particles at an 11% nominal level, 8% level, 6% level and 4% level
by weight. Using a 2-liter glass reactor, the lab scale EA formulation
black parent particles were aggregated, coalesced, washed, and then
freeze dried.

[0071] It will be appreciated that several of the above-disclosed and
other features and functions, or alternatives thereof, may be desirably
combined into many other different systems or applications. Also that
various presently unforeseen or unanticipated alternatives,
modifications, variations or improvements therein may be subsequently
made by those skilled in the art which are also intended to be
encompassed by the following claims.